This invention pertains generally to missile guidance systems, and particularly to an improved guidance system wherein missile lateral and longitudinal acceleration signals are combined with a line-of-sight rate signal and a closing velocity signal to derive the requisite guidance signals.
As it is known, most homing missiles utilize a proportional navigation guidance system wherein signals representative of the missile line-of-sight rate and closing velocity between the missile and a target are used to derive the requisite guidance control signals. The signals representative of the closing velocity and line-of-sight rate are multiplied by an effective navigation ratio, N.sup.1, to develop acceleration commands that are used to control actual missile acceleration. In a benign environment (meaning in the absence of countermeasures), target maneuver, scintillation noise and angle noise in the missile seeker are major contributors to causing a high miss distance in a proportional navigation guidance system. In a hostile environment (meaning countermeasures are present), homing missiles employing a proportional navigation guidance system are particularly vulnerable to multiple blinking jammers and velocity gate pulloff jammers.
As it is also known, a multiple blinking jammer provides a jamming signal whose spectrum covers the bandpass of the victim radar with a duty cycle (i.e. blinking rate) that confuses the victim radar, whereas a velocity gate pulloff jammer produces a signal which, when received by the victim radar, causes the victim radar to loose velocity tracking of the target. With either multiple blinking jamming or velocity gate pulloff jamming, such techniques cause the victim radar to loose track of the target. Thus, the victim radar must go into a reacquistion mode to reacquire the target.
Accordingly, it would be desirable to provide a guidance system which will produce appropriate command signals to facilitate reacquisition of the target when the guidance system returns to a target reacquisition mode.